This Friday, when “Jurassic World” — the fourth movie in the popular “Jurassic Park” franchise — hits theaters, brace yourselves for the birth of a whole new generation of dino-devotees.

Backyards all across Maine will become sites of scientific exploration, as junior paleontologists excavate, hoping to find a complete, perfectly preserved T-rex or velociraptor skeleton.

Unfortunately for all those would-be Jack Horners and Paul Serenos, their dino-digs are almost certainly doomed, and not just because they’ll be conducted with garden trowels and beach toys.

No dinosaur fossils have ever been discovered in Maine, and it’s likely none ever will.

“There probably were dinosaurs here — they’ve been found as close by as Nova Scotia and western Massachusetts — but we have no way of knowing for sure,” says Dr. David Work, chief scientist and curator of geology at the Maine State Museum and associate editor of the Journal of Paleontology.

The reason for the dearth of dinosaur remains is a nearly 300-million-year gap in Maine’s fossil record.

The glaciers responsible for carving out Maine’s distinctive craggy landscape during the Pleistocene Epoch — a period between about 2.5 million and 12,000 years ago — abraded more than 400 feet of earth from the state’s surface, scouring away a massive chunk of geological history in the process.

As a result, all of the fossils found in Maine so far date from either the past 12,000 years, after the last glacier receded, or from more than 400 million years ago, during a warm, fertile age called the Devonian Period (named for Devon County, England, where fossils from the period were first discovered, not for new-wave band Devo).

The first land animals didn’t emerge from the ocean — and there was only one ocean, dubbed Panthalassa by scientists, that covered 85 percent of the planet — until the end of that period.

The dinosaurs appeared much later: They walked the earth between about 250 and 65 million years ago.

The ocean, however, was teeming with life during the Devonian Period, so fossils from that time found in what is now Maine are more likely to evoke “20,000 Leagues Under the Sea” than “Jurassic Park.”

The most common type of fossils found in Maine are brachiopods, shelled clam-like organisms that lived in shallow ocean water. Like most bivalve mollusks today — a family that includes clams, scallops and mussels — prehistoric brachiopods buried themselves in the sediment, leaving behind impressions of their shells as the bedrock formed over time.

Then, when glaciers scraped away the top layers of the landmass that eventually became Maine, they scattered fragments of fossilized rock around for modern-day rockhounds to find.

Work, at the Maine State Museum, says people come into the museum 20 to 30 times a year with brachiopod fossils they’ve found, wanting to learn more about them.

“They’re pretty little things, one or two inches long.”

Other forms of sea life are also common finds.

“We’ve seen fossils that are starfish-like, jellyfish-like, corals, snails, sponges and trilobites, a kind of predecessor to horseshoe crabs,” says Dr. Robert Marvinney, Maine state geologist.

While brachiopod fossils bear a close resemblance their modern relatives, trilobites look more like the alien prehistoric creatures they were. Their flat, ridged, oval bodies ranged in size from about an inch long to two feet. The marine arthropods were among the most successful early organisms on earth, reigning over the oceans for more than 270 million years before becoming extinct about 250 million years ago.

Maine’s state fossil: pertica quadrifaria

As interesting as the sci-fi-like trilobites are, Marvinney says the most significant fossil found in Maine, by far, comes from a plant.

Maine’s state fossil is pertica quadrifaria, a primitive plant that evolved during the Devonian Period. Fossilized remains of the plant were first discovered in 1968 in the rocks of the Trout Valley Formation in Baxter State Park, not far from Mount Katahdin.

Pertica featured stems that measured about an inch in diameter, with branches arranged in four rows that spiraled up and around the stem. Some branches featured spore cases for reproduction, and others subdivided to form forked tips that were probably the first step in the evolution of leaves.

It was the largest land plant at that time, reaching heights of about six feet.

While a prehistoric plant may lack the coolness factor of dinosaurs, pertica was incredibly important, because it was among the very first plants on Earth to develop a vascular system — veins that allowed it to transport water from its roots to the rest of the plant.

This innovation allowed the plant to not only grow larger than a few inches, but also to move inland, away from constant water sources, for the first time in evolutionary history, ultimately resulting in the development of many modern plant species, including trees.

“By the end of the Devonian Period, some probably reached about 100 feet tall,” says Work.

The fact that Maine was, at the time, a tropical location sitting well below the equator, explains how the massive plants were able to thrive.

Their development and proliferation were critical to the rise of animal and human life on the planet.

“Early land plants, like pertica, are responsible for the abundance of oxygen in our atmosphere,” says Work.

This, in turn, paved the way for more animals to move from the oceans and onto the land.

Pertica fossils are also exciting to scientists and geology buffs because they are incredibly rare. Well-preserved remains of pertica have been found in only three other places in the world besides what is now Maine.

Because of its evolutionary importance, and because of its rarity and the fact that it was first discovered in Maine, pertica quadrifaria was designated Maine’s official state fossil in 1985.

Maine’s likely dinosaur inhabitants

Fossils are more than just an interesting oddity for kids and science buffs, though. Maine’s fossil record has played an important role in helping geologists piece together a picture of not just what life on earth looked like hundreds of millions of years ago, but also what the earth, itself, looked like.

For instance, some brachiopod fossils found in Maine are more similar to those seen in Europe than in neighboring states. That and similar discoveries around the world have helped geologists form a picture of how the Earth’s land masses were once shaped, and how tectonic activity has changed the continents over time.

Scientists believe there were two continents, Laurasia and Gondwana, during the Devonian Period, when most of Maine’s fossils were formed.

“This was a very tumultuous time, with a lot of tectonic activity. This was right after the collision that formed the Appalachian Mountains,” says Marvinney.

The earth’s land masses were still moving during the Jurassic period, when dinosaurs roamed.

And while no dinosaur fossils have ever been found in Maine, discoveries in Nova Scotia, western Massachusetts and Connecticut shed light on what types of dinosaurs likely walked the land that eventually became Maine, and when.

Ammosaurus: At about 13 feet in length, ammosaurus was on the small side for a dinosaur. It was a versatile creature that was able to move on either two or four legs, and is also believed to have been omnivorous. It lived during the early and middle Jurassic Period, between 200 and 160 million years ago. Remains have been found in Nova Scotia and Connecticut.

Anchisaurus: A small herbivorous dinosaur possibly related to ammosaurus, anchisaurus was believed to be about six feet long, including the tail, and stood less than half the height of an average human. It lived during the early Jurassic Period, between 200 and 188 million years ago. Remains have been found in Nova Scotia, Massachusetts and Connecticut.

Plateosaurus: A bipedal herbivore with a very small head atop a long pliable neck, plateosaurus ranged from 16 to 33 feet long and weighed anywhere between 1,300 and 8,800 pounds. It lived during the late Triassic Period, around 214 to 204 million years ago. Remains have been found in Nova Scotia.

Podokesaurus: A small carnivorous dinosaur that was about three feet long and one foot tall, podokesaurus is believed to have been very nimble and fast. Its name comes from the Greek for “swift-footed lizard.” It lived during the early Jurassic Period, between 200 and 188 million years ago, and is one of the earliest known dinosaurs to inhabit the eastern United States. Remains have been found in Massachusetts.

Although dinosaur remains have never been found in Maine, geologists say they have many other reasons for appreciating the remnants of the past that can be found here.

Marvinney says he enjoys working with Maine’s fossil record to piece together the earth’s past and enjoys understanding how minerals found in the earth are essential to every facet of modern civilization — from the development of agriculture to the silicone now used in computer chips.

Work, at the museum, says he has a lot in common with all of those kids who’ll soon be making messes of their parents’ lawns. “Every kid seems to be interested in rocks and fossils. I just never outgrew it.”

Where to see fossils in Maine

* Maine Geological Survey office, 93 State House Station, Augusta; 207-287-2801; http://www.maine.gov/dacf/mgs/about/index.shtml

The state keeps a small collection of Maine fossils in their reference collection.

* Maine State House, State Street, Augusta; 207-287-2301; http://legislature.maine.gov/general/1246/1246/

Several of the black limestone floor tiles in the Maine State House contain fossilized remains of marine invertebrates. The limestone was sourced from Vermont, though, so the fossils are not native to Maine. The tiles were installed over a 22-year period between 1889 and 1911, but the fossils were not discovered for nearly a century. Legislative employee and fossilphile Patrick Norton first recognized the fossils in stones outside the Governor’s Office, under the dome and in hallways in 1992.

* L. C. Bates Museum, 16 Prescott Drive, Hinckley; 207-238-4250; http://www.gwh.org/lcbates/LCBatesMuseum.aspx

Features an exhibit of native fossil specimens.

* Maine Discovery Museum, 74 Main St., Bangor; 207-262-7200; https://www.mainediscoverymuseum.org/

Kids can dig for and reconstruct life-size replicas of dinosaur fossils in the Dino Dig exhibit.

* Maine State Museum, 230 State St., Augusta; 207-287-2301; http://www.mainestatemuseum.org/

There are many fossil specimens here, including a large stone slab featuring Maine’s official state fossil, pertica quadrifaria.

* Northern Maine Museum of Science, 181 Main St., Presque Isle; 207-768-9482; http://pages.umpi.edu/~nmms/museum.htm

Many fossil specimens are on display, including Maine trilobites and non-native dinosaur fossils on loan from other institutions. A quetzalcoatlus northropi specimen — a flying dinosaur similar to a pteradactyl — is currently on exhibit.

* The Nylander Museum, 657 Main St., Caribou; 207-493-4209; http://www.nylandermuseum.org

This town-sponsored natural history museum is named after Swedish-born paleontologist Olof Nylander, who served as the original curator and whose personal collection is housed there. The museum also features non-native dinosaur fossils and other loaned exhibits.